חַמּוּקֵי יְרֵכַיִךְ כְּמוֹ חֲלָאִים מַעֲשֵׂה יְדֵי אָמָּן
and notes that the rashei teivos can be arranged to form the words חסורי מחסרא והכי קתני. He adds that there are 130 chisurei mechsara's in Shas, the gimatriya of ירך. (The editor of the sefer notes that we only find 99 of them, so he suggests that such cases as תני כך וכך to the number. In any event, the gimatriya is not relevant to the yesod.)
Reb Shamshon states that there is a wonderful secret to this concept. It does not mean that the Mishnah is missing some essential words that should have been there. For why would R' Yehuda HaNasi not made sure to include them in the first place?
He includes in this secret the Gemara's occasional statement הך תנא ברישא וחזר בו ומשנה לא זזה ממקומה. Why didn't R' Yehuda HaNasi remove the original Mishnah from Shas?
Reb Shamshon explains that all Mishnayos are really Sheimos HaKodesh. That is why R' Yehuda HaNasi was limited in his options by the tzirufei sheimos. The example he gives is from the Mishnah in Shabbos 106b ישב השני ומלאוה השני חייב - the Shem Hashem in the rashei teivos.
Thus, he says, the meaning of חסורי מחסרא והכי קתני: Even though it seems to be חסורי מחסרא, nevertheless, הכי קתני - this is the way it had to be written, on account of the tzirufei sheimos.
The editor explains that חלאים means "jewelry" - so the pasuk should be understood:
The 120 "hidden" passages are gems, fashioned by an expert craftsman - that you should not think that they are missing "by accident" - but by deliberate plan.